230 



N. W. Shock 



subjects were selected only after a thorough history and physi- 

 cal examination which excluded recent or remote renal 

 diseases, cerebrovascular accidents, coronary artery disease, 

 syphilitic or rheumatic heart disease, hypertension, or any 

 recent alterations in body weight. All tests were carried out 

 under basal conditions and subjects were hydrated with 600- 

 800 ml. water, given orally 1-2 hours before the test, and 

 200 ml. water were given at half-hour intervals during the 



40 60 60 



AGE-YEARS 



Fig. 1. Change in standard diodrast clearance or effective renal 



plasma flow with age. O O average values ml. plasma/min./ 



1-73 sq. m. body surface area. 

 (From: Shock, 1952). 



test. The constant infusion method was followed, and four 

 clearance and four Tm periods of 10-14 minutes each were 

 taken according to the method of Smith, Goldring and Chasis 

 (1938). Fig. 1 shows the age change in effective renal plasma 

 flow as estimated from diodrast clearance (Shock, 1952). 

 Between the ages of 20 and 90 years there was a decline in the 

 effective renal plasma flow amounting to approximately 53 

 per cent. The regression equation relating the diodrast 

 clearance to age is: Clj^ = 840 — 6-44 X age (in years). 



